The present invention relates to a radial piston machine with at least one spherical piston, and more particularly to a spherical piston pump, whose balls adapted to roll on an outer cam ring or stator are connected rotatably to a cylindrical sleeve which slides in a sealed manner in a radial bore of a rotor rotatable on a stationary control pintle which is provided with supply and discharge channels.
A spherical piston machine of the construction referred to hereinabove is known from German Patent DE-OS No. 2,908,096. The slidable cylindrical sleeve disposed in a snug fit relative to the rotor's radial bore leaves a gap between rotor and sleeve due to which losses caused by leaks have to be put up with, which impair the efficiency of the machine, in particular in the event of higher pressures and/or the operating medium being of low viscosity.